57+ distributor in a 54 Merc 256 motor?


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By oldcarmark - 15 Years Ago
I was explaining the advantage of using the dual advance late distributor in place of the original loadomatic to an aquaintance who has a 54 Merc 256 motor.What needs to be changed in order to use the late distributor in his Y-block?Seem to recall that the 54 dist. gear and oil pump shaft are not the same as used in the 55+ Y-block.What do you do-swap the old drive gear onto the late distributor?what about the oil pump shaft?Do you need to change the oil pump to the newer style also?
By Daniel Jessup - 15 Years Ago
I have never seen a 256, but seems I remember that although it is early, it has the dizzy with the hex design shaft - maybe somebody can correct me if I am wrong here. If it doesn't have that shaft, it may just be a simple matter of changing out the existing shaft because I believe that the 256 has the same tooth count on the camshaft as does the 272-312. Also, the EBU camshaft and the EBV camshafts have different tooth counts for the distributor drive gear. Believe the EBV has the same as the 272-312 Y's.

Of course, the carb/distributor match problem also comes into play as well.

Maybe somebody a "little" bit older than I am will chime in here...Tongue

By aussie-y - 15 Years Ago
i have a 256 mercury block & cam in my 56 vicky the rest of the motor is 272 crank, rods & heads. the dissy gear in the 256 merc. is i think 13 teeth on the drive gear where as the 272-292-312,s are 14 teeth
By oldcarmark - 15 Years Ago
What dizzy are you using?The original loado or the later one  with the gear switched from the original dizzy?What oil pump shaft are you using?
By Ted - 15 Years Ago
To use a ’57 and up distributor in a 1954 239 or 256 engine, the 1954 oil pump and distributor drive will also need to be swapped out with the later model units.  The ’54 engines have a tanged oil drive and oil pump while the ’55 and later engines use a hex drive and corresponding oil pump.  The distributor gear off of the ’54 distributor will need to be used on the ’57 distributor as the 1954 camshaft requires the 13 tooth distributor gear.  The 1954 engines have a larger journaled camshaft which in turn requires keeping the appropriate distributor gear in place.
By Hoosier Hurricane - 15 Years Ago
In addition to what Ted posted, you will also need a '57 and later distributor cap and rotor.
By 314 - 15 Years Ago
i never had a problem with the early dist, and carb setup as long as everything was in good shape.if i was going to make changes to the engine then i would go to the later setup.
By John Mummert - 15 Years Ago
I'm pretty sure that only the 239 is oddball and the 256 has the normal cam bearings and dist gear.

If that is correct you will only need to change the oil pump and drive rod.

By aussie-y - 15 Years Ago
my 256 cam bearings are larger od than the 272 -292,and it has a 13 tooth drive gear